Apparatus for pulverizing coal



Sept. 24, 1929. H. M. NOBIS 1,728,975

APPARATUS FOR PULVERIZING COAL I Filed Oct. 5, 192'! 2 Sheets-Sheet 1 Harte; M. Nobis Inventor MM/VZWM Attornegs Sept. 24, 1929. H. M. NOBIS APPARATUS FOR PULVERIZING GOAL Filed Oct. 1927 2 Sheets-She Hat-r3 Nobis Inventor Attornegs Patented Sept. 24, 1929 PATENT OFFICE HARRY M. 110318, or user CLEVELAND, onto APPARATUS FOR PULVERIZING COAL Application filed October 8, 1927. Serial No. 223,569.

This invention relates to the burning of pulverized coal and has for its objects the provision of a very simple, compact, inexpensive, and efiicient feeder and pulverizer for taking commercial granular coal and delivering it to a burner properly comminuted and mixed with air in the requisite proportions.-

The advantages of burning pulverized coal carried into the furnace by an air stream are recognized and have proven highly successful, but those advantages heretofore have been confined to large installations because of the ponderous and expensive character of the machinery employed. An important object of my invention is the provision of a device of this character which is so simple and compact as to render it economical for use in installations of very much smaller s ze, such as for small power and heating plants, locomotives, and even for domestic use.

In the drawings accompanying and forming a part of this application I have shown one physical structure in which my inventive ideas can be embodied though without intent to limit myself to the particular forms or arrangements therein shown. Fig. 1 is a vertical central sectional view and Figs. 2, 3, 4, and 5 are horizontal sectional views corresponding to the similarly numbered lines of Fig. 1 and looking inv the direction of the various arrows accompanying those lines; and Fig. 6 illustrates a modification.

Describing the parts herein shown by the use of characters of reference appearing on the drawing, 1 denotes a base which carries three upright legs 2 having flaring upper ends 3 which embrace a hopper 4. Secured 40 to the base under the center of the hopper is an upright hollow support 5 having a flange 6 at its upper end on which is mounted a flat annular plate 7 formed around its periphery with gear teeth 8. The upper face of this plate is horizontal and is located rather close to the lower end of the hopper, air leakage being here prevented by the use of a flexible metal sealing-ring 9. Mounted in one wall of the support 5 is a horizontal. ad 10 on which is rotatably mounted a gear 11, one side of which meshes with the teeth 8 while the opposite side meshes with the worm 12 carried by the shaft of the electric motor 13. A ball-bearing 14 is shown between the flange 6 and plate 7.

Located inside the support 5 below the level of the plate 7 is a wind-box 15, annular in shape, having a flat top 16 formed with a plurality of spaced apertures 17 arranged preferably in concentric rows. The bottom of the box is closed with a removable plate 18, while its side wall 19 is formed at one point' with a lateral neck 20 to which is attached the air inlet pipe 21.

Supported inside the hopper is a hollow cylindrical casing 24 having its open lower end spaced a sufiicient distance above the hopper-bottom 7 to define an adequate coal inlet, and having its upper end narrowed to a neck 25 which is connected to the inlet 26 of a fan casing 27. This fan casing is secured in its turn, by any suitable means such as the brackets 28, to a second fan casing 29 whose outlet 30 is connected to the pipe 21. This upper fan casing in turn is connected by means of the arms 32 to brackets 33 carried by the three members 34 of a tripod carried by the legs 2 and supporting the motor 35.

Traversing the three casings and wind-box is a vertical shaft, supported y a thrust bearing 36 at the bottom and connected to the motor shaft 37 by a flexible clutch 38 at the top. In the resent embodiment I have shown this sha t as made in two parts, name- 1y a part 40 of comparatively small diameter at the upper end fitting tightly into a hollow part 41 of larger diameter at the lower end, and carried by the lower section of said shaft are a plurality of beaters adapted,

at least when the shaft is rotated, to project at right angles therefrom and sweep about the chamber. Obviously these beaters could, consist of arms rigid with the shaft, but I prefer, as a safeguard against breakage, to make them of joined nature and to this end I preferably make each beater-arm of a section of chain 42, suitably secured in the shaft so that when straightened out by the centrifugal force of the rotation it may sweep close to the side Walls of the chamber without- The fan casing 27 has its outlet 47 connected to a pipe 48 leading to a furnace or burner (not shown); The arms 32 define an inlet opening 50 for air. I have here shown the two fan chambers as covered by a circular, bell-shaped, hood 51 which dips slightly into the hopper to guard against dust; Secured to the lower end of the shaft 41 near the top of the wind-box are one or more spreader arms 52.

' Carried by the top of the wind-box is a vertical bearing sleeve 53 in which is journaled the shank 54 of a scraper 55 adapted to overlap the plate 7 a greater or less degree for the purpose of assuring a constant supply of coal. The position of this scraper is adjusted in any suitable manner as by the screw rod 56 assing through one wall of the support 5 and wind-box 15 where it is articulated to a radial arm 57 carried by the shank. Also mounted inside the wind-box is a circular register plate 58 having apertures adapted, as the same is revolved, to register more or less completely with apertures 17 thereby controlling the air supply. This plate is here connected by means of a suitable link 59 with the arm 57 so as to be adjustable by the same movement which controls the scraper 55.

The plate apertures of the innermost row are preferably elongated circumferentially of the plate as shown in Fig. 5 so as to leave the central row of the apertures 17 open at all times for the purpose of providing a minimum airflow; those of the second row are preferably also made oval but less oblong so as to come into register in advance of the outermost apertures which are left circular. The size and design of the fan 46 and its chamber 29 are so chosen as to produce the necessary flow of air at a higher outlet pressure than is produced by the fan 45 and its chamber 27. It is necessary that the pressure produced in the pipe 21 besufiiciently great to keep the apertures clear at all times and even to clear the top of the wind-box though it should accidentally become deeply covered with coal. The function of the fan 45 is to maintain such negative pressure inside the hood as to prevent escape of dust-laden air through the supply of coal with which the hopper is more or less filled, and also to convev the dust-laden resultant air to the burner.

Coal forburning in this manner is ordinarily delivered in the form of rather fine screenings running up to a size of perhaps one-fourth inch lumps. The operation is started as follows: the register plate 58 is assumed .tobe closed when the mechanism is at rest. After the hopper has been properly filled with granular coal the motor 35 is first started which creates an upward blast of air through whatever apertures of the wind-box are open, and this blast elevates the coal granules. 1nto the range of the rapidly. rotating beater-arms which flail them and hammer them rapidly'by impact to a condition of fine dust. The vertical ribs 43 or other projections with which the chamber wall is formed assist in th s by arresting the motion given the particles by the beater arms and preventmg any tendency to swirl about the chamber.

Even though the force of the blast be only sufiiclent to lift the granules part way into the.

chamber, from which they would fall again in the absence of the heaters, yet the action of the heaters serves to break up those particles so rapidly as to cause them to remain in suspension in the comparatively'weaker air current which exists at this point. Ordinarily the suction of the fan 45 is sufficient to prevent outward leakage of dust-laden air through the coal in the hopper, but if for an reason suchleakage should occur, the final escape of dust is prevented by the hood 51 which overlies the inlet 50 and causes all the entering air to sweep over the mouth of the hopper. Sufficient gap is left around this hood to permit ready replenishment of the coal supply. I v

It is not always necessary 'to make the bottom plate ofthe hopper rotatable or to provide other mechanical means for assuring the inward movement of the coal granules.-

If the parts be so designed that the angle of the coal face is greater than the angle of repose and the coal be sufiiciently dry so as not to cohere it is obvious that a flow will occur, and this flowing tendency is always assisted by the vibration of the parts which vibration can itself be increased for this purpose by making the lower end of the shaft slightly unbalanced. However, the rotatable bottom plate 7 herein shown constitutes a refinement which is oftentimes valuable in that it assures a-feeding of coal even when wet and sticky, it creates a more uniform'feeding of the coal, and it permits designing the coal inlet opening between the casing 24 and hopper bottom to produce a slope of the fuel less than the angle of repose so' that cascading of the coal will not occur when the apparatus is at rest. It will be obvious that-much the same final result can be achieved by making the bottom plate fixed and providing one or more rotatable scrapers 55 as by making the scraper fixed and the plate movable relative thereto. Such end with a fixed annular flange 7 constituting the hopper bottom. The lower end of the shaft, preferably reduced in diameter as at 41 is surrounded by a loose sleeve 65 which carries one or more scrapers 66 that sweep 'over the flange'7 and also with the spreader-s52. In this view I have shown the shaft-extension 41" as mounted on radial anti-friction rollers 67 while the sleeve 65 is mounted on the hubs of these rollers so as to be rotated by friction and at a lower speed than the shaft 41. Also in Fig. 6 1 have shown a clean-out door 68 in the side of the support 5 to enable the removal of stones, metal articles, and other accidental foreign matter, this feature not being shown in the cross section on which Fig. 1 is taken.

I have illustrated a separate motor 13 to rotate ,t-he plate 7 in order to render it independent of the motor both in use and speed, but it will be obvious that in cases where the rotatable bottom plate is used any suitable driving connection can be employed therewith. It will also be obvious that the use of a vertical motor direct connected to the main shaft is not in'iperative since other driving connections can likewise be employed at this point; also 'it will be obvious that the two fans and 46 need not be carried on the same shaft with the heaters or with each other or with the motor although I have combined these features in such a way to produce a device of minimum complexity and maximum utility. It will be obvious that additional features may be incorporated or advantages omitted without departing from my inventive idea or avoiding a proper construction of these my Letters Patent, and I do not limit myself to any of the features herein illustrated and particularly described but only as specifically recited in my several claims with bencfit of equivalents in accordance with the state of the art.

Having thus described my invention what I claim is:

1. In a device of the character described,

in combination a casing having a vertical chamber, means for suppplying an under pressure to the lower end of said chamber, means for aspirating such air from the upper end of said chamber, means for delivcring granular coal to the interior of said chamber at a point above the air inlet, and means in said chamber for breaking said coal into fine particles during its elevation therethrough by the air stream.

2. In a device of the character described, in combination a :asing having a vertical chamber, means for supplying air under pressure to the lower end of said chamber, means for aspirating such air from the upper end of said chamber, means for delivering granular coal to the interior of said chamber at a point above the air inlet, avertical shaft in said chamber, impact arms carried by said shaft, and means for rotating said shaft.

3. In a device of the character described, in combination a casing having a vertical chamber, means for supplying air under pressure to the lower end of said chamber, means for aspirating such air from the upper end of said chamber, means for delivering granular coal to the interior of said chamber at a point above the air inlet, a vertical shaft in said chamber, means for rotating said shaft, and jointed impact arms carried by said shaft adapted to sweep past the chamber wall as said shaft is rotated.

4. In a device of the character described, in combination, a chambered casing, a shaft projecting through said casing, beater arms carried by said shaft, means for rotating said shaft, means for feeding air under pressure vertically upwards into the bottom end of said chamber and withdrawing it from the top end of said chamber, and means for feeding granular coal to the interior of said chamber.

5. In a device of the character described, in combination, a chambered casing, a shaft projecting through said casing, arms carried by said shaft of a length to extend near to the chamber walls, two rotary air pumps located outside of said chamber operatively connected to said shaft and communicating with opposite ends of said chamber, one with its inlet and the other with its outlet, and means for feeding granular coal to the interior of the chamber.

6. In a device of the character described,

in combination, a chambered casing, a shaft projecting through said casing, arms carried by said shaft of a length to extend near to the chamber walls, two rotary air pumps operatively connected to said shaft and communicating with opposite ends of said chamber, one being designed to produce a higher pressure than the other, the high pressure fan having its outlet connected to said chamber and the low pressure fan having its inlet connected to said chamber, and means for feeding granular coal to the interior of said chamber. 7 In a device of the character described, in combination, a chambered casing, two rotary air-pumping devices of unequal pressure production, the high pressure device having its outlet connected to one end of said chamber and the lower pressure device having its inlet connected to the other end of said chamber, means for feeding granular coal to said chamber, and means in said chamber for breaking said coal into fine particles during its passage therethrough.

8. In a device of the character described, in combination a casing having a vertical chamber, a vertical shaft therein, two fans carried by said shaft, casings for said fans,

means connecting the top of said first casing to the inlet of one fan'casing .a d its lower end to the outlet of the other an casing, means for feeding granular coal to said first chamber, arms ,'carried by said shaft inside said chambera'dapted to strike and break up the coal, and means forrotating said shaft.

9. In a device of the character described,

in combination, a hopper, an upright chambered casing therein which communicates with said hopper at its lower end, means for supplying air under pressure to said chamber at a point below its communication with said hopper and for withdrawing the air under suction from the up er endof said casing, and ge plurality of rotatlng beaters in said chamity of coal breaking arms carried by said shaft inside said chamber.

11. In a device of the characterdescribed, in combination, a wind-box having apertures on its upper face, a hollow casing supported above said wind-box and defining therewith a chamber, means for supplying air under pressure to said wind-box, means for withdrawing air from the top of said chamber, means for feeding granular coal to said chamber above the top of said wind-box, and means in said chamber to break up the coal therein.

12. In a device of the character described, in combination, a hopper having an annular bottom, a Wind-box in said bottom and having an apertured upper face, a chambered casing located inside said hopper over said wind-box and defining with the hopper bottom a coal inlet, means for delivering air under pressure to said wind-boxand withdrawing air under suction from said casing, means for creating a'gradual inflow of coal through said inlet, and means for pulverizing the coal which enters said casing.

13. In a device of the character described, in combination, a vertical impact mill, means for feeding granular coal to the lower end thereof, and two centrifugal air fans, one of the same having its outlet discharging into the lower end of said impact, and the other having its inlet connected to the upper end of said impact mill for carrying away the resultant coal dust from the upper end thereof.

14. In a device of the character described, in combination, a vertical impact'mill, two centrifugal fans, one adapted and arranged to discharge into the lower end of said mill and the other having its inlet communicating with the upper end of said mill, and means centrifugal fans, one adapted and arranged.

to discharge into the lower end of said mill and the other having its inlet communicating with the upper end of said mill, and means for feeding granular coal to the air stream below such mill.

16. In a device ofthe character described, in combination, a coal comminuting device, a hopper for granular coal connected to said device, means including an air fan for trans porting the coal through said comminuting device, and a suction hood overhanging said hopper and connected to the suction s1de of a fan. a

' 17 In a device for producing and transporting powdered coal, in combination an. air ox having upwardly directed discharge openings, a suction hood overlapping and spaced vertically from said air box, pulverizing apparatus located between said air box and hood, two air fans, one having its inlet communicating with the interior of said hood andits outlet connected to said air box, the other having its inlet connected to said ulverizing apparatus, and means for fee ing coal to be pulverized to said apparatus at a point between said hood and air box.

'In testimony whereof I hereunto aflix my signature.

' HARRY M. NOBIS. 

